ruleguard,analyzer: change Report() callback argument

Pass a structure with a set of fields instead of
passing them as separate arguments.

This makes it easier to add more (potentially experimental)
match context arguments without breaking the API.

But this time we have to break the API once.

AST walker now saves current function name (and type name if it's
a method). This can be useful in filters later, so we can match
the current function name/type in `Where()` expressions.

analyzer/analyzer.go

@@ -3,7 +3,6 @@ package analyzer
 import (
 	"bytes"
 	"fmt"
-	"go/ast"
 	"go/token"
 	"io/ioutil"
 	"os"
@@ -105,17 +104,19 @@ func runAnalyzer(pass *analysis.Pass) (interface{}, error) {
 		Sizes:        pass.TypesSizes,
 		Fset:         pass.Fset,
 		GoVersion:    goVersion,
-		Report: func(info ruleguard.GoRuleInfo, n ast.Node, msg string, s *ruleguard.Suggestion) {
-			fullMessage := msg
+		Report: func(data *ruleguard.ReportData) {
+			fullMessage := data.Message
+			info := data.RuleInfo
 			if printRuleLocation {
 				fullMessage = fmt.Sprintf("%s: %s (%s:%d)",
-					info.Group.Name, msg, filepath.Base(info.Group.Filename), info.Line)
+					info.Group.Name, data.Message, filepath.Base(info.Group.Filename), info.Line)
 			}
 			diag := analysis.Diagnostic{
-				Pos:     n.Pos(),
+				Pos:     data.Node.Pos(),
 				Message: fullMessage,
 			}
-			if s != nil {
+			if data.Suggestion != nil {
+				s := data.Suggestion
 				diag.SuggestedFixes = []analysis.SuggestedFix{
 					{
 						Message: "suggested replacement",

analyzer/testanalyzer/testanalyzer.go

@@ -2,7 +2,6 @@ package testanalyzer
 
 import (
 	"fmt"
-	"go/ast"
 	"go/token"
 	"path/filepath"
 
@@ -26,11 +25,13 @@ func New(ruleSet *ir.File) *analysis.Analyzer {
 			Types: pass.TypesInfo,
 			Sizes: pass.TypesSizes,
 			Fset:  pass.Fset,
-			Report: func(info ruleguard.GoRuleInfo, n ast.Node, msg string, s *ruleguard.Suggestion) {
+			Report: func(data *ruleguard.ReportData) {
+				info := data.RuleInfo
+				msg := data.Message
 				fullMessage := fmt.Sprintf("%s: %s (%s:%d)",
 					info.Group.Name, msg, filepath.Base(info.Group.Filename), info.Line)
 				pass.Report(analysis.Diagnostic{
-					Pos:     n.Pos(),
+					Pos:     data.Node.Pos(),
 					Message: fullMessage,
 				})
 			},

ruleguard/ast_walker.go

@@ -13,6 +13,20 @@ type astWalker struct {
 	visit func(ast.Node)
 }
 
+func (w *astWalker) getTypeName(typeExpr ast.Expr) string {
+	switch typ := typeExpr.(type) {
+	case *ast.Ident:
+		return typ.Name
+	case *ast.StarExpr:
+		return w.getTypeName(typ.X)
+	case *ast.ParenExpr:
+		return w.getTypeName(typ.X)
+
+	default:
+		return ""
+	}
+}
+
 func (w *astWalker) Walk(root ast.Node, visit func(ast.Node)) {
 	w.visit = visit
 	w.walk(root)
@@ -306,6 +320,15 @@ func (w *astWalker) walk(n ast.Node) {
 		if n.Doc != nil {
 			w.walk(n.Doc)
 		}
+		prevTypeName := w.filterParams.currentTypeName
+		prevFuncName := w.filterParams.currentFuncName
+		w.filterParams.currentFuncName = n.Name.Name
+		if n.Recv != nil {
+			if len(n.Recv.List) != 0 {
+				w.filterParams.currentTypeName = w.getTypeName(n.Recv.List[0].Type)
+			}
+			w.walk(n.Recv)
+		}
 		if n.Recv != nil {
 			w.walk(n.Recv)
 		}
@@ -314,6 +337,8 @@ func (w *astWalker) walk(n ast.Node) {
 		if n.Body != nil {
 			w.walk(n.Body)
 		}
+		w.filterParams.currentTypeName = prevTypeName
+		w.filterParams.currentFuncName = prevFuncName
 
 	case *ast.File:
 		w.walk(n.Name)

ruleguard/debug_test.go

@@ -254,7 +254,7 @@ func newDebugTestRunner(input string) (*debugTestRunner, error) {
 		Types: &info,
 		Sizes: types.SizesFor("gc", runtime.GOARCH),
 		Fset:  fset,
-		Report: func(info GoRuleInfo, n ast.Node, msg string, s *Suggestion) {
+		Report: func(data *ReportData) {
 			// Do nothing.
 		},
 	}

ruleguard/gorule.go

@@ -67,6 +67,9 @@ type filterParams struct {
 
 	deadcode bool
 
+	currentFuncName string
+	currentTypeName string
+
 	// varname is set only for custom filters before bytecode function is called.
 	varname string
 }

ruleguard/perf_test.go

@@ -49,7 +49,7 @@ func benchRunContext(b *testing.B, src string) (*RunContext, *ast.File) {
 		Types: typesInfo,
 		Sizes: types.SizesFor("gc", runtime.GOARCH),
 		Fset:  fset,
-		Report: func(info GoRuleInfo, n ast.Node, msg string, s *Suggestion) {
+		Report: func(data *ReportData) {
 			// Do nothing.
 		},
 	}

ruleguard/ruleguard.go

@@ -93,15 +93,32 @@ type RunContext struct {
 	DebugImports bool
 	DebugPrint   func(string)
 
-	Types  *types.Info
-	Sizes  types.Sizes
-	Fset   *token.FileSet
-	Report func(rule GoRuleInfo, n ast.Node, msg string, s *Suggestion)
-	Pkg    *types.Package
+	Types *types.Info
+	Sizes types.Sizes
+	Fset  *token.FileSet
+	Pkg   *types.Package
+
+	// Report is a function that is called for every successful ruleguard match.
+	// The pointer to ReportData is reused, it should not be kept.
+	// If you want to keep it after Report() returns, make a copy.
+	Report func(*ReportData)
 
 	GoVersion GoVersion
 }
 
+type ReportData struct {
+	RuleInfo   GoRuleInfo
+	Node       ast.Node
+	Message    string
+	Suggestion *Suggestion
+
+	// Experimental: fields below are part of the experiment.
+	// They'll probably be removed or changed over time.
+
+	FuncName string
+	TypeName string
+}
+
 type Suggestion struct {
 	From        token.Pos
 	To          token.Pos

ruleguard/runner.go

@@ -23,6 +23,8 @@ type rulesRunner struct {
 	ctx   *RunContext
 	rules *goRuleSet
 
+	reportData ReportData
+
 	gogrepState gogrep.MatcherState
 
 	importer *goImporter
@@ -291,7 +293,16 @@ func (rr *rulesRunner) handleCommentMatch(rule goCommentRule, m commentMatchData
 		Group: rule.base.group,
 		Line:  rule.base.line,
 	}
-	rr.ctx.Report(info, node, message, suggestion)
+	rr.reportData.RuleInfo = info
+	rr.reportData.Node = node
+	rr.reportData.Message = message
+	rr.reportData.Suggestion = suggestion
+
+	// Experimental stuff.
+	rr.reportData.TypeName = rr.filterParams.currentTypeName
+	rr.reportData.FuncName = rr.filterParams.currentFuncName
+
+	rr.ctx.Report(&rr.reportData)
 	return true
 }
 
@@ -322,7 +333,16 @@ func (rr *rulesRunner) handleMatch(rule goRule, m gogrep.MatchData) bool {
 		Group: rule.group,
 		Line:  rule.line,
 	}
-	rr.ctx.Report(info, node, message, suggestion)
+	rr.reportData.RuleInfo = info
+	rr.reportData.Node = node
+	rr.reportData.Message = message
+	rr.reportData.Suggestion = suggestion
+
+	// Experimental stuff.
+	rr.reportData.TypeName = rr.filterParams.currentTypeName
+	rr.reportData.FuncName = rr.filterParams.currentFuncName
+
+	rr.ctx.Report(&rr.reportData)
 	return true
 }